my check engine light stays on..the radiator fan runs constantly and continues to run after i shut off the car and the temperture gauge isnt working. i have a 2001 monte carlo. the diagnostic code for the problem is 128. i changed the water temp sensor a couple weeks ago and it seemed to take care of the problem for a week. all the same problems again. any suggestions?

 

I just fixed this, i had the exact problem - the thermostat was stuck wide open -

 

I'm having the EXACT same problem. I can't believe it! They want to charge for diagonostic and on and on. Did the thermostat solve the problem? And were you getting any heat. I am! Everyone seems to think it is not the thermostat cause I am getting heat!

 

ive heard this many times where the t stat is wide open that you will not get any heat cause it is not slowing down the coolant enough to let it warm up. but its also not slowing it down to cool. good fix

 

I'm not only getting a check engine light (which just started yesterday) but last week I had a "low coolant level" light so I added coolant. My engine fan keeps running after turning car off, and I can't afford anything! I have a 2001 Monte Carlo LS. Any help on this would be appreiciated. Any ideas on how to fix this as inexpensively as I can. Still need to get to work.

 

how much coolant did you add? was it considerably low? did the light go out when you added coolant? how many miles on the car? can you smell coolant under the hood of the car?

 

Had same exact problem. I changed the engine coolant temp sensor, but also had to reset the computer in order for everything to work. Do yourself a favor and replace the stock thermostat with a Stant Super Stat Premium. It's only a few extra dollars but it doesn't work like the stock one. It opens slowly metering the coolant flow allowing the engine to warm up to operating temps in even in extreme cold weather.

 

The light actually didn't come on till the next day. My son added the coolant but the overflow was very low. I will try the other suggestions on here first. I sure am broke and certainly think a 4 yr old car shouldn't have this kind of problems. Also..one other thing, both my elec windows wont work up or down. Do you know what parts I need to get and approx $? I hear that can be pretty expensive as well. I've got little rubber stoppers in them holding them up right now...i know..sounds ghetto, but $ is tight right now. Seems like everything started goin bad at 73k miles. I used to be able to work on cars...you know...the old ones with normal old time carburators..floats...remember the day...these new computer things have me bonkers. Anyway, where do i get to the computer to reset it after replacing the engine coolant temp sensor?

 

I'm assuming you have checked the fuse for the windows? Don't know what else to do for that one.
To reset computer just disconnect the NEGATIVE cable to the battery. Let it sit for at least 10 min(I usually wait an hour), then reconnect it. Start the car and see what results you get.

 

Your windows won't stay up by themselves ??? That's wierd..... sounds like something mechanical is disconnected.